Substrate processing method, substrate processing apparatus and software

Abstract

To perform highly uniform etching processing on a substrate using an etching gas containing at least one of ammonia gas and amine gas, in each part of the surface of the substrate.SOLUTION: An etching method of the present disclosure performs: a step for supplying each of a first etching gas and a second etching gas including at least one of ammonia gas and amine gas from a gas supply source to a gas supply channel; a storing step for storing the first etching gas and the second etching gas in a reservoir provided in the gas supply channel to raise the pressure inside the reservoir; and a gas supply step for etching a first film formed on a substrate by opening a valve provided downstream of the reservoir in the gas supply channel and supplying the first etching gas and the second etching gas stored in the reservoir to a processing vessel with the substrate stored inside.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present disclosure relates to a substrate processing method, a substrate processing apparatus, and software. [Background technology]

[0002] When processing substrates such as semiconductor wafers (hereinafter referred to as wafers), gases temporarily stored in tanks may be released into a processing vessel to perform the processing. Patent Document 1 describes that He, HCl, and SF6 gases stored in tanks are released to perform an etching process on substrates for manufacturing flat panel displays (FPDs). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5235293 Summary of the Invention [Problem to be solved by the invention]

[0004] The present disclosure provides a technology that enables highly uniform etching of a substrate at each portion of the surface of the substrate using an etching gas containing at least one of ammonia and amine gas. [Means for solving the problem]

[0005] The etching method of the present disclosure includes the steps of: supplying a first etching gas and a second etching gas containing at least one of an ammonia gas and an amine gas from a gas supply source to a gas supply path; a storing step of storing the first etching gas and the second etching gas in a storage portion provided in the gas supply path and increasing the pressure inside the storage portion; a gas supplying step of opening a valve provided downstream of the reservoir in the gas supply path to supply the first etching gas and the second etching gas stored in the reservoir to a processing vessel containing a substrate therein, thereby etching a first film formed on the substrate; An etching method comprising: [Effects of the Invention]

[0006] The present disclosure makes it possible to perform etching on a substrate using an etching gas containing at least one of ammonia and amine gas, with the result that the etching can be performed with high uniformity across the surface of the substrate. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a longitudinal sectional front view of an etching apparatus according to an embodiment of the present disclosure. [Figure 2] FIG. 2 is a vertical cross-sectional side view of the etching apparatus. [Figure 3] FIG. 2 is a schematic perspective view showing the inside of the etching apparatus. [Figure 4] 3 is a timing chart of a process performed by the etching apparatus. [Figure 5] 5A to 5C are diagrams illustrating the operation of the etching apparatus. [Figure 6] 5A to 5C are diagrams illustrating the operation of the etching apparatus. [Figure 7] 1 is a schematic diagram showing a vertical cross section of the surface of a wafer to be etched; [Figure 8] 1 is a schematic diagram showing a vertical cross section of the surface of a wafer to be etched; [Figure 9] 1 is a schematic diagram showing a vertical cross section of the surface of a wafer to be etched; [Figure 10] 1 is a schematic diagram showing a vertical cross section of the surface of a wafer to be etched; [Figure 11] 1 is a schematic diagram showing a vertical cross section of the surface of a wafer to be etched; [Figure 12]1 is a schematic diagram showing a vertical cross section of the surface of a wafer to be etched; [Figure 13] 10 is a timing chart of another process performed by the etching apparatus. [Figure 14] 5A to 5C are diagrams illustrating the operation of the etching apparatus. [Figure 15] 10 is a timing chart of another process performed by the etching apparatus. [Figure 16] 10 is a timing chart for explaining a process in an evaluation test. DETAILED DESCRIPTION OF THE INVENTION

[0008] 1 and 2 show a longitudinal sectional front view and a longitudinal sectional side view, respectively, of an etching apparatus 1 which is one embodiment of the etching apparatus of the present disclosure and which performs the etching method of the present disclosure. An outline of the process performed in the etching apparatus 1 will be described first. This etching apparatus 1 etches the surface of the wafer W under a desired pressure in a vacuum atmosphere by using a halogen-containing gas and a basic gas as etching gases. Note that no plasma is generated around the wafer W during this etching.

[0009] The wafer W transported to the etching apparatus 1 has a first film, SiOx (silicon oxide) film 101, and a second film, SiN (silicon nitride) film 102, formed thereon, each of which is exposed on the surface of the wafer W. Both the SiOx film 101 and the SiN film 102 are etchable by the etching gas. That is, when a halogen-containing gas, which is the first etching gas, and a basic gas, which is the second etching gas, are supplied together, both the SiOx film 101 and the SiN film 102 are etched.

[0010] The etching apparatus 1 is configured to selectively etch the SiOx film 101 out of the SiOx film 101 and the SiN film 102 with high uniformity across the surface of the wafer W. More specifically, the etching apparatus 1 performs the selective etching by utilizing the difference in incubation time between the SiOx film 101 and the SiN film 102 with respect to the etching gas (halogen-containing gas and basic gas). The incubation time is the time from when the gas is adsorbed onto the film on the substrate until it starts to react with the film.

[0011] The halogen-containing gas is a fluorine-containing gas, more specifically, hydrogen fluoride (HF) gas, and the basic gas is NH3 (ammonia) gas or an amine gas. More specifically, trimethylamine (TMA) gas is used as the amine gas. When these etching gases are used, the incubation time of the SiOx film 101 is shorter than that of the SiN film 102. In other words, immediately after both the halogen-containing gas and the basic gas are supplied to the wafer W, the SiOx film 101 is etched, while the SiN film 102 is not etched.

[0012] In the etching apparatus 1, the wafer W is stored in the processing chamber 11 and the processing chamber 11 is in an evacuated state, while the etching gas described above is stored in a tank and pressurized. The etching gas is then released from the tank into the processing chamber 11. This allows the etching gas to quickly diffuse into the processing chamber 11. The supply of the etching gas is then stopped relatively soon after it starts. By stopping the supply of the etching gas and evacuating the processing chamber 11, the etching gas is removed from the processing chamber 11, preventing the SiN film 102 from being etched.

[0013] The supply and cutoff of the etching gas into the processing vessel 11 is performed by a valve provided downstream of the tank. By repeatedly opening and closing this valve at a relatively high speed, the SiOx film 101 is selectively etched and the desired etching amount is achieved. As described above, the etching gas released from the tank quickly diffuses within the processing vessel 11, thereby reducing variations in the timing at which the etching gas is adsorbed at various locations within the surface of the wafer W, resulting in highly uniform etching within the surface of the wafer W.

[0014] The tanks provided are a tank for a halogen-containing gas and a tank for a basic gas. That is, HF gas and NH3 gas or TMA gas are stored in separate tanks (tanks 81 and 82). This prevents the halogen-containing gas and the basic gas from reacting with each other while stored in the tanks. In accordance with the provision of a tank for each gas type, the valves V1 and V2 are provided downstream of tank 81 and tank 82, respectively.

[0015] In this example, the opening and closing timings of the valves V1 and V2 are synchronized. That is, the period during which HF gas is supplied into the processing vessel 11 coincides with the period during which NH3 gas or TMA gas is supplied into the processing vessel 11. Two wafers W are stored in the processing vessel 11, and are mounted on stages 5 arranged side by side in the processing vessel 11. The above-described etching process is performed on the two wafers W in the same manner and simultaneously. This improves the throughput of the apparatus.

[0016] Next, a schematic configuration of the etching apparatus 1 will be described with reference to the perspective view of Fig. 3 showing the interior of the apparatus. The processing vessel 11 constituting the etching apparatus 1 is composed of a lid 12 and a vessel body 13. The vessel body 13 forms the side and bottom walls of the processing vessel 11. The vessel body 13 includes an outer wall portion 14 and an inner wall portion 15, each of which has a recessed shape in a vertical cross-sectional view. The inner wall portion 15 is located within the outer wall portion 14, so that the side and bottom walls of the processing vessel 11 form a double wall.

[0017] A processing space forming member 41 is provided surrounded by the inner wall portion 15. The processing space forming member 41 is a member for dividing the area surrounded by the container body 13 into left and right halves, thereby forming two processing spaces 4 for processing wafers W, respectively. The processing space forming member 41 is movable up and down so as not to interfere with the transfer of the wafer W to the stage 5. Hereinafter, the two processing spaces 4 may be referred to as processing spaces 4A and 4B to distinguish them from each other.

[0018] Two shower plates 3 are provided on the underside of the lid 12 of the processing vessel 11, spaced apart from each other on the left and right. Together with a processing space forming member 41, they form processing spaces 4A and 4B, and supply gas to the processing spaces 4A and 4B, respectively. A stage 5 for supporting a wafer W is provided in each processing space 4A and 4B. Each stage 5 is movable up and down, allowing the wafer W to be positioned at a desired height for processing. The processing spaces 4A and 4B are evacuated through an exhaust port 28 that opens in the center of the left and right sides of the bottom of the vessel body 13.

[0019] Next, the configuration of each part of the etching apparatus 1 will be described in detail. In the following description, the shower plate 3 that forms the processing space 4A and the shower plate 3 that forms the processing space 4B will sometimes be referred to as 3A and 3B, respectively, to distinguish them from each other. Furthermore, the stage 5 that is provided in the processing space 4A and the stage 5 that is provided in the processing space 4B will sometimes be referred to as 5A and 5B, respectively, to distinguish them from each other. Incidentally, among the components used to process the wafer W in the processing space 4A and the components used to process the wafer W in the processing space 4B, the same components are designated by the same numerals. Furthermore, the left-right direction and the front-back direction are respectively indicated as the X direction and the Y direction, which are perpendicular to each other, in the drawings.

[0020] The upper end of the inner wall portion 15 constituting the vessel body 13 expands outward to form a flange 16, and the flange 16 is supported from below by the upper end of the outer wall portion 14. The inner wall portion 15 is detachable from the outer wall portion 14. A gap 17 is formed between the outer wall portion 14 and the inner wall portion 15. As will be described later, holes for raising and lowering the stage 5 and the processing space forming member 41 within the processing vessel 11 and holes for exhaust are formed in various locations on the inner wall portion 15 and the outer wall portion 14. An O-ring 37 serving as a sealing member is provided along the edge of each of these holes and is in close contact with the outer wall portion 14 and the inner wall portion 15. As a result, the gap 17 does not communicate with these holes, forming an airtight space.

[0021] An inert gas is supplied to and exhausted from gap 17 via a gas supply pipe and an exhaust pipe (not shown) connected from the outside of processing vessel 11, and gap 17 is maintained at a relatively low pressure during processing of wafer W. This prevents gas from leaking from processing space 4 to the outside of processing vessel 11 and provides thermal insulation from the outside of processing vessel 11 to processing space 4.

[0022] Furthermore, through holes 18 and 19 are formed in the front wall portions of the outer wall portion 14 and the inner wall portion 15 that form the container body 13, respectively, and these through holes 18 and 19 overlap each other in the front-to-rear direction (Y direction) (see FIG. 2). The through holes 18 and 19 are slit-shaped and long in the left-to-right direction (X direction), and a tubular member 21 that is long in the left-to-right direction is in close contact with the circumferential surfaces that form the through holes 18 and 19, and is provided so as to extend front-to-rear from the through hole 18 to the through hole 19.

[0023] The area surrounded by the cylindrical member 21 is configured as a transfer port 22 for the wafer W, and the wafer W passes through the left and right areas of the transfer port 22 to be delivered to the stages 5A and 5B. The transfer port 22 is opened and closed by a gate valve 23 provided on the front side of the outer wall 14. The wafer W is transferred into and out of the processing chamber 11 through the transfer port 22 by a transfer mechanism (not shown).

[0024] The periphery of the lid 12 is supported on a flange 16 of the inner wall 15 via a heater (not shown) formed along the flange 16. Shower plates 3 (3A, 3B) are provided on the underside of the lid 12, spaced apart from each other on the left and right. The shower plates 3 are circular in plan view, and each include a diffusion space 32 that diffuses gas horizontally, and a gas outlet port 33 connected to the diffusion space 32. A large number of gas outlet ports 33 are formed and distributed on the underside of the shower plate 3, and each opens toward the upper surface of the stage 5.

[0025] A flow path forming section 34 is provided on the upper side of the lid 12 of the processing vessel 11. A piping system 6, which will be described later, is connected to this flow path forming section 34, and gas supplied from this piping system 6 is supplied to the diffusion spaces 32 of the shower plates 3A and 3B through flow paths formed in this flow path forming section 34. The line for supplying the etching gas described above in the piping system 6 is shared by the shower plates 3A and 3B. The flow paths in the flow path forming section 34 are configured to distribute the etching gas supplied from the line to each of the diffusion spaces 32 of the shower plates 3A and 3B.

[0026] Two through holes 24 are formed at a distance from each other on the left and right sides in the bottom of the inner wall 15 that constitutes the container body 13. The portions of the bottom of the outer wall 14 that overlap the through holes 24 are configured as bottom forming portions 10. A lower inner wall 25, which is an upright cylinder, is provided on each bottom forming portion 10. The body of the lower inner wall 25 is located within the through holes 24, and the upper end of the lower inner wall 25 expands outward at a position above the through holes 24 to form a flange 26. In addition, an exhaust passage 27, which is a through hole, is formed in the side wall below the lower inner wall 25, and the inside and outside of the lower inner wall 25 communicate via the exhaust passage 27.

[0027] An exhaust port 28 is formed at the bottom of the outer wall 14, between the positions of the aforementioned through holes 24 in the left-right direction. A through hole 29 is formed at the bottom of the inner wall 15 above the exhaust port 28, and the exhaust port 28 can exhaust air from the area surrounded by the inner wall 15 through the through hole 29. One end of an exhaust pipe 20 is connected to the bottom of the outer wall 14 from below, so as to open to the exhaust port 28. The other end of the exhaust pipe 20 is connected to an exhaust mechanism 2A via a valve V10. The exhaust mechanism 2A is composed of, for example, a turbomolecular pump, a dry pump, or the like, and the pressure inside the processing vessel 11 is adjusted by adjusting the opening of the valve V10.

[0028] The processing space forming member 41 will now be described in detail. The processing space forming member 41 is formed to extend left and right, and has two through holes 42 formed in the vertical direction, spaced apart on the left and right. Each through hole 42 is a hole for forming the processing space 4, and is circular in plan view. The upper edge of the processing space forming member 41 expands outward to form an upper flange 43. In addition, an O-ring 38 is provided on the upper hole edge of each through hole 42, following the periphery of the through hole 42.

[0029] The lower end of each through hole 42 protrudes toward the central axis of the through hole 42 to form a lower flange 44, and an O-ring 39 is provided on the lower flange 44 along the periphery of the through hole 42. The lower flange 44 is located below the flange 26 of the lower inner wall 25. Of the circumferential surface forming the through hole 42, the portion above the lower flange 44 is shown as an inner circumferential surface 45.

[0030] The processing space forming member 41 is supported at its lower center on the left and right sides by support columns 46, which penetrate the bottom of the processing vessel 11 and are connected to an elevating mechanism 47 provided outside the processing vessel 11. Reference numeral 48 in the figure denotes a flange provided on the support columns 46 outside the processing vessel 11. Reference numeral 49 in the figure denotes a bellows that can expand and contract in the vertical direction, which surrounds the support columns 46 and is connected to the flange 48 and the bottom of the processing vessel 11 to ensure airtightness inside the processing vessel 11. The positions at which the support columns 46 and the elevating mechanism 47 are provided are shifted rearward with respect to the position where the exhaust port 28 is formed. The elevating mechanism 47 raises and lowers the processing space forming member 41 between an upper processing position and a lower standby position.

[0031] 1 and 2 show the processing space forming member 41 at the processing position and the standby position, respectively. At the processing position, the O-ring 38 on the upper flange 43 is in close contact with the periphery of the shower plate 3, and the O-ring 39 on the lower flange 44 is in close contact with the flange 26 of the lower inner wall 25. As a result, spaces surrounded by the shower plate 3, the processing space forming member 41, the lower inner wall 25, and the bottom of the outer wall 14 are formed on the left and right sides of the processing vessel 11. A stage 5 is provided in each space, and the area above the stage 5 in each space is the processing space 4. Each processing space 4 is evacuated from the exhaust port 28 via the exhaust path 27 in the lower inner wall 24. As shown in FIG. 2, the upper end of the processing space forming member 41 at the standby position is located below the transfer port 22, allowing a wafer W to be transferred into the processing vessel 11.

[0032] In addition, shafts 40 are provided extending downward from the left and right sides of the upper flange 43 and penetrating the inner wall 15 and the outer wall 14. The shafts 40 serve to prevent the processing space forming member 41 from shaking when it is raised and lowered. Like the support columns 46, the shafts 40 are also provided with flanges 48 and are surrounded by bellows 49 connected to the flanges 48 and the bottom of the processing vessel 11, thereby ensuring airtightness inside the processing vessel 11.

[0033] As described above, when forming the exhaust path within the processing vessel 11, a protective film is formed on portions of the processing vessel 11 that are in contact with or likely to be in contact with the etching gas to prevent corrosion by the etching gas. Therefore, this protective film is made of a different material from the base material constituting the processing vessel 11. Specifically, the protective film is formed on the circumferential surface and bottom surface of the inner wall 15 facing the processing space 4, and on the upper surface of the bottom-forming portion 10 constituting the outer wall 14. The inner wall 15 and the bottom-forming portion 10 are detachable from the other portions constituting the processing vessel 11, facilitating maintenance of the device. The base material of the processing vessel 11 is, for example, aluminum, and the material of the protective film may be selected appropriately depending on the etching gas used. When HF gas, NH3 gas, and TMA gas are used as in this example, the protective film is made of, for example, Ni (nickel).

[0034] Next, the stages 5 (5A, 5B) will be described. Each stage 5 is circular in plan view, with its upper surface facing the lower surface of the shower plate 3 and its side facing the inner circumferential surface 45 forming the through-hole 42 of the processing space forming member 41. The upper side of the stage 5 is configured as an electrostatic chuck, which adsorbs the wafer W placed on the upper surface of the stage 5. A fluid flow path 51 is formed on the lower side of the stage 5. A temperature-adjusted fluid is supplied to the flow path 51 by a temperature adjustment mechanism (not shown), thereby adjusting the wafer W adsorbed to the stage 5 to a desired temperature. Note that fluid supply pipes and discharge pipes for the flow path 51 are connected to the stage 5, but are not shown.

[0035] The upper end of an enclosure 52, which is concave in cross section when viewed from the vertical direction, is connected to the lower part of each stage 5, and a horizontal plate 53 is provided in an enclosed space surrounded by the enclosure 52 and the underside of the stage 5. Three pins 54 (only two are shown in the figure) extending vertically are provided on the horizontal plate 53. The horizontal plate 53 is connected to a support 55 that penetrates the bottom of the enclosure 52 and the bottom-forming portion 10 of the processing vessel 11, and the lower end of the support 55 is connected to an elevation mechanism 56 provided outside the processing vessel 11. The pins 54 for supporting the wafer W are raised and lowered on the upper surface of the stage 5 by the elevation mechanism 56, and transfer the wafer W between the stage 5 and a transfer mechanism (not shown). Note that in the figure, reference numeral 50 denotes a through-hole provided in the stage 5, through which the pins 54 are inserted.

[0036] Furthermore, columns 57 supporting surrounding portion 52 from below are provided penetrating bottom forming portion 10 of processing vessel 11 and connected to an elevating mechanism 58 provided outside processing vessel 11. Bellows 59, which surrounds columns 57 and 55 and is expandable and contractible in the vertical direction, is provided surrounded by lower inner wall 25. An upper end of bellows 59 is connected to the periphery of surrounding portion 52 and a lower end of bellows 59 is connected to the bottom of outer wall 14, and similar to bellows 49, it serves to ensure airtightness inside processing vessel 11.

[0037] Incidentally, the support columns 57, the lifting mechanism 58, and the bellows 59 are provided for each stage 5. Therefore, the heights of the stages 5A and 5B can be adjusted individually, but in this example, the heights of the stages 5 are aligned so that the same processing is performed on the wafers W on the stages 5A and 5B. Note that the fact that the stage 5 can be raised and lowered in this way means that the volume of the processing space 4, which is the region above the stage 5, can be adjusted.

[0038] Next, the piping system 6 will be described. The piping system 6 includes pipes 61, 62, 63, and 64, the downstream ends of which are connected to the flow path forming portion 34. The pipes 61 and 62 are connected to the shower plates 3A and 3B, respectively. The upstream sides of the pipes 61 and 62 are connected to N2 gas supply sources 71A and 71B, respectively, via flow rate adjustment mechanisms 60. The flow rate adjustment mechanisms 60 are configured with valves and mass flow controllers, and switch on and off the supply of gas to the downstream sides of the flow paths and adjust the flow rate of the gas. Note that the flow rate adjustment mechanisms 60 provided on pipes other than the pipes 61 and 62, which will be described later, have the same configuration as the flow rate adjustment mechanisms 60 provided on the pipes 61 and 62. The N2 (nitrogen) gas supplied from the N2 gas supply source 71 serves as a carrier gas for the etching gas and as a purge gas for purging the processing chamber 11.

[0039] The pipes 63 and 64 are configured as gas flow paths in which storage portions are interposed. The downstream end of the pipe 63 is connected to the shower plates 3A and 3B via a flow path in the flow path forming portion 34. A valve V1, a tank 81, and a valve V3 are interposed in this order upstream of the pipe 63. The pipe 63 branches upstream of the valve V3 to form pipes 63A and 63B. The pipe 63A is connected to an HF gas supply source 72 via a flow rate adjustment mechanism 60. The pipe 63B is connected to an N2 gas supply source 73 via a flow rate adjustment mechanism 60. The N2 gas supplied from the N2 gas supply source 73 is a dilution gas for the HF gas. The valve V3 is opened while the gases are supplied to and stored in the tank 81, which is the first storage portion, and is closed while the first valve V1 is open to prevent the gas stored in the tank 81 from flowing back through the pipe 63.

[0040] The downstream end of the pipe 64 is connected to the shower plates 3A and 3B via the flow path of the flow path forming unit 34. A valve V2, a tank 82, and a valve V4 are disposed in this order upstream of the pipe 64. The pipe 64 branches upstream of the valve V4 to form pipes 64A, 64B, and 64C. A flow rate adjustment mechanism 60 is disposed in each of the pipes 64A to 64C. The upstream ends of the pipes 64A, 64B, and 64C are connected to a TMA gas supply source 74, an NH gas supply source 75, and an N gas supply source 76, respectively. Either NH gas or TMA gas is supplied toward the tank 82. The N gas supplied from the N gas supply source 76 is a dilution gas for the NH gas and the TMA gas. Valve V4 is open while the gases are being supplied to and stored in tank 82, which is the second storage section, and is closed while valve V2, which is the second valve, is open to prevent the gases stored in tank 82 from flowing back through piping 64.

[0041] Each of the tanks 81 and 82 is provided with a pressure sensor 80, which transmits a detection signal indicating the pressure within the tanks 81 and 82 to a control unit 90 (described later). The control unit 90 can detect the pressure within the tanks 81 and 82 based on the detection signal. The detection signal is transmitted to the control unit 90 at intervals shorter than 100 milliseconds, specifically, at intervals of 10 milliseconds, for example, and the control unit 90 can detect the pressure within the tanks 81 and 82 at the same intervals. This pressure detection interval is shorter than the time it takes for the valves V1 and V2 to transition from one open state to the other. Therefore, as described later, the opening and closing of the valves V1 and V2 changes the processing steps performed on the wafer W, and it is possible to detect the pressure within the tanks 81 and 82 for each step and determine whether or not there is an abnormality.

[0042] As shown in FIG. 1, the etching apparatus 1 includes a control unit 90, which is a computer. The control unit 90 includes software, a memory, a CPU, an operation unit, and an alarm output unit. The operation unit is a data input device that allows the user of the etching apparatus 1 to make various settings, and is configured, for example, by a touch panel. The operation unit can be used to configure operation settings for when an abnormality occurs in the pressure inside tanks 81 and 82, which will be described later, and various settings related to the processing recipe. The various settings are stored in the memory of the control unit 90. The alarm output unit is configured, for example, by a display and a speaker, and notifies the user of abnormalities and determination results, which will be described later, by displaying a predetermined screen or sounding a predetermined alarm.

[0043] The software incorporates commands (steps) for processing wafers W, which will be described later, and this software is stored on a storage medium, such as a compact disc, hard disk, memory card, magneto-optical disc, or DVD, and is installed in the control unit 90. The control unit 90 outputs control signals to each component of the etching apparatus 1 using the software, and controls the operation of each component, thereby performing processing on the wafers W. Specifically, the control unit 90 controls operations such as opening and closing valves V1 to V4, adjusting the aperture of valve V10, supplying gases to the downstream sides of the pipes using flow rate control mechanism 60, adjusting the height of stage 5 using lifting mechanism 58, raising and lowering processing space forming member 41 and pins 54 using lifting mechanisms 47 and 56, and opening and closing transfer port 22 using gate valve 23.

[0044] The software includes a program for detecting the pressure in the tanks 81 and 82 from the detection signal, determining whether the detected pressure is within a predetermined range, and taking appropriate action if the detected pressure is determined not to be within the predetermined range. Examples of appropriate action include stopping the ongoing processing of the wafer W and outputting an alarm, outputting an alarm and stopping the processing of the next wafer W to be transferred to the apparatus (while continuing the ongoing processing of the wafer W), or only outputting an alarm without stopping the processing of the wafer W. An action preset by the user is selected from these options.

[0045] Before processing the wafer W, the user selects a processing recipe for the wafer W. The processing recipe is a combination of parameters related to processing conditions for the wafer W, and is stored in the memory of the control unit 90. Specific examples of the individual parameters that make up the combination include the pressure within the processing vessel 11, the processing temperature of the wafer W, and parameters related to each gas supplied into the processing vessel 11. The parameters related to each gas include parameters related to the timing and flow rate of gas supply to the downstream side by each flow rate adjustment mechanism 60, and the timing of opening and closing the valves V1 to V4.

[0046] The software includes a program that assists in creating a processing recipe. This program calculates the pressures in the tanks 81 and 82 based on parameters input by the user before processing the wafer W, and determines whether the calculated values ​​are appropriate. The determination of whether the calculated values ​​are appropriate includes determining whether the pressures in the tanks 81 and 82 storing gases are within an allowable range (i.e., whether they exceed an upper threshold or a lower threshold), as well as determining whether the pressure difference between the tanks 81 and 82 when both valves V1 and V2 are switched to an open state is within an allowable range. If the calculated values ​​are determined not to be within the allowable range, the program is configured to output an alarm to that effect from an alarm output unit.

[0047] Regarding the determination of the pressure difference between the tanks 81 and 82, as described above, in this example, the downstream valves V1 and V2 of the tanks 81 and 82 are simultaneously opened to supply each gas toward the shower plate 3. If the pressure difference between the tanks 81 and 82 is too large, gas supplied from one of the tanks 81 and 82 will flow toward the other tank via the shower plate 3. In other words, a backflow of gas occurs in the piping system 6. This may cause an undesired reaction between the gases, preventing proper processing of the wafer W. To prevent such a problem, the program determines the pressure difference as described above and outputs an alarm if the settings are inappropriate, prompting the user to reset the parameters. This method of determining the pressure difference will be described in detail after describing an example of the operation of the etching apparatus 1.

[0048] Next, an example of operation of the etching apparatus 1 will be described with reference to the timing chart of FIG. 4, and FIGS. 5 and 6 showing the gas supply state to the processing chamber 11 and the gas flow within the processing chamber 11. Also, FIGS. 7 to 12 showing schematic diagrams of changes in the surface of the wafer W will be referred to as appropriate. Note that although TMA gas is used in this example, processing can be performed in a similar manner when NH gas is used instead of TMA gas.

[0049] The timing chart in Fig. 4 shows pressure changes in tanks 81 and 82, the open / close states of valves V1 and V2, the timing of HF gas supply to tank 81, the timing of TMA gas supply to tank 82, and pressure changes in processing vessel 11 (i.e., pressure changes in processing space 4). Note that the pressure in processing vessel 11 changes depending on the opening of valve V10, so this pressure change chart also shows changes in the opening of valve V10. In Figs. 5 and 6, for each pipe constituting piping system 6, the portion through which gas flows is shown thicker than the other portions. In some of Figs. 7 to 12, HF gas is shown schematically as 103 and TMA gas is shown as 104.

[0050] First, two wafers W are transferred into the processing vessel 11 by the transfer mechanism while the processing space forming member 41 is waiting at the waiting position and the stage 5 is waiting at a relatively low position so as not to interfere with the transfer of the wafers W. Fig. 7 shows the surfaces of the wafers W thus transferred into the processing vessel 11. These wafers W are respectively attracted to the stages 5 via the pins 54 and heated to a desired temperature, for example, -20°C to 150°C.

[0051] After the transfer mechanism is retracted from the processing vessel 11, the processing space forming member 31 is raised to the processing position, and the processing space 4 is formed. Each stage 5 is raised to a predetermined height position and approaches the shower plates 3A and 3B, respectively. Then, N2 gas is supplied from the N2 gas supply sources 71A and 71B to the processing spaces 4A and 4B via the shower plates 3A and 3B, respectively, while the aperture of the valve V10 is adjusted to a predetermined aperture (hereinafter referred to as a first aperture), and the processing spaces 4A and 4B in the processing vessel 11 are set to a predetermined pressure.

[0052] Valves V1 and V2 are closed, and valves V3 and V4 are opened. Then, HF gas and N2 gas are started to be supplied from HF gas supply source 72 and N2 gas supply source 73 to empty tank 81, and TMA gas and N2 gas are started to be supplied from TMA gas supply source 74 and N2 gas supply source 76 to empty tank 82 (time t1 in the chart, FIG. 6). Each gas is stored in tank 81 and 82, and the pressure inside tank 81 and 82 increases from the initial pressure (first pressure) before the gas supply started. When the inside of tank 81 and 82 reaches a desired second pressure (hereinafter referred to as the discharge pressure), valves V3 and V4 are closed, and valves V1 and V2 are opened (time t2). Also, at this time t2, the opening of valve V10 is changed to a predetermined second opening that is larger than the first opening, and the flow rate control mechanism 60 stops the supply of HF gas, TMA gas, and N2 gas to tanks 81 and 82.

[0053] By opening the valves V1 and V2, the gases stored in the tanks 81 and 82 are released into the processing spaces 4A and 4B, respectively, and quickly diffuse throughout the processing space 4 (FIG. 6). Furthermore, by changing the opening of the valve V10 to the second opening, the pressures in the processing spaces 4A and 4B are reduced to a predetermined pressure (referred to as the "other pressure"). This pressure reduction also allows the gases to quickly diffuse throughout the processing spaces 4A and 4B. The reason why the pressures in the processing spaces 4A and 4B are kept relatively high (referred to as the "first pressure") at the moment the gases are released from the tanks 81 and 82 is to prevent problems caused by an excessively large pressure difference between the tanks 81 and 82 and the processing spaces 4A and 4B. Specifically, this prevents the wafer W from being misaligned due to the pressure of the supplied gas and prevents particles from being stirred up by the airflow generated within the processing vessel 11. The first and second pressures in the processing spaces 4A and 4B are within a range of 0.133 Pa to 666 Pa, for example.

[0054] The HF gas 103 and TMA gas 104 diffused into the processing spaces 4A and 4B are adsorbed onto the entire surface of the wafer W, i.e., the entire surface of each of the SiOx film 101 and the SiN film 102 (FIG. 8). Then, due to the difference in incubation time described above, etching of only the SiOx film 101 out of the SiOx film 101 and the SiN film 102 begins (FIG. 9). Thereafter, for example, before the pressures in the tanks 81 and 82 return to the initial pressure, the valves V1 and V2 are closed (time t3), and the gas supply from the tanks 81 and 82 to the processing spaces 4A and 4B is stopped. The pressure in the tanks 81 and 82 at this time is referred to as a standby pressure (third pressure). By quickly closing the valves V1 and V2, in this example, the relationship (standby pressure - initial pressure) > (release pressure - standby pressure) holds.

[0055] The HF gas 103 and the TMA gas 104 are removed from the processing spaces 4A and 4B by exhausting the processing spaces 4A and 4B and purging with N2 gas supplied from the N2 gas supply sources 71A and 71B. Because the processing spaces 4A and 4B are maintained at a relatively low pressure, the removal of the HF gas 103 and the TMA gas 104 proceeds efficiently, and the concentrations of the HF gas 103 and the TMA gas 104 in the processing spaces 4A and 4B decrease rapidly. Due to this decrease in concentration, the HF gas 103 and the TMA gas 104 adsorbed on the SiOx film 101 and the SiN film 102 are desorbed from the SiOx film 101 and the SiN film 102 into the processing spaces 4A and 4B (FIGS. 10 and 11). Therefore, the etching of the SiOx film 101 stops, and the initiation of etching of the SiN film 102 is inhibited.

[0056] Thereafter, valves V3 and V4 are opened, and the flow rate control mechanism 60 resumes supplying HF gas and N2 gas to the tank 81 and TMA gas and N2 gas to the tank 82. At the same time, the valve V10 returns to the first opening (time t4), and the pressure in the processing spaces 4A and 4B increases and returns to the same pressure. Therefore, at time t4, the same operation as at time t1 is performed, and the state of the processing vessel 11 returns to the state shown in FIG. 5.

[0057] When the pressure in the tanks 81 and 82 rises from the standby pressure to the discharge pressure, the same operation as at time t2 is performed. That is, the valves V3 and V4 are closed, the valves V1 and V2 are opened, the valve V10 is changed to the second opening, and the supply of HF gas, TMA gas, and N2 gas to the tanks 81 and 82 by the flow rate control mechanism 60 is stopped (time t5). Therefore, the operation of the apparatus at time t5 is the same as the operation at time t2. As a result, the gases stored in the tanks 81 and 82 are discharged into the processing spaces 4A and 4B, while the pressure in the processing spaces 4A and 4B drops to the other pressures. The processing vessel 11 returns to the state shown in FIG. 6, and selective etching of the SiOx film 101 is resumed.

[0058] Thereafter, as at time t3, valves V1 and V2 are closed (time t6), and the HF gas 103 and TMA gas 104 are removed from processing spaces 4A and 4B, stopping the progress of etching of the SiOx film 101 and inhibiting the start of etching of the SiN film 102. Then, valves V3 and V4 are opened, restarting the supply of HF gas and N2 gas to tank 81 and the supply of TMA gas and N2 gas to tank 82, and returning valve V10 to its first opening (time t7). That is, at time t7, the apparatus operates in the same manner as at time t4. Then, when the pressure in tanks 81 and 82 rises from the standby pressure to the discharge pressure, the same operations as at times t2 and t5 are performed (time t8).

[0059] In this way, from time t5 to t8, the series of operations from time t2 to t5 is performed again. Then, similar operations are repeated from time t8 onwards. By performing the cyclic operation in this way, selective etching of the SiOx film 101 is repeated. When a predetermined number of cycles are completed and the etching amount of the SiOx film 101 reaches a desired amount (FIG. 12), each wafer W is unloaded from the processing chamber 11 in the reverse order of the loading procedure into the processing chamber 11.

[0060] As described above, first, a step (initial storage step) of storing gas in the tanks 81 and 82 is performed. After that, the wafer W is processed by repeating a cycle consisting of a gas release step of releasing gas from the tanks 81 and 82 into the processing space 4, an exhaust step of stopping the release of gas from the tanks 81 and 82 and exhausting each gas from the processing space 4, and a re-storage step of supplying the released gas to the tanks 81 and 82. The exhaust step and the re-storage step are performed in parallel.

[0061] The period during which the gas release step is performed is the period during which the valves V1 and V2 are open, and corresponds to the period between times t2 and t3 and the period between times t5 and t6. The period during which one gas release step is performed is relatively short, for example, less than one second. Therefore, in the above processing example, when the valves V1 and V2 are opened, not all of the gas in the tanks 81 and 82 is released into the processing space 4, and some remains. Therefore, the initial storage step (between times t1 and t2) in which gas is stored in the empty tanks 81 and 82 is longer than the re-storage steps (between times t4 and t5, and between times t7 and t8).

[0062] As described above, in the etching apparatus 1, relatively large amounts of HF gas and TMA gas pressurized by being stored in the tanks 81 and 82 are released into the processing space 4 by opening the valves V1 and V2. Therefore, the HF gas and TMA gas are distributed throughout the processing space 4 in a short time, and the HF gas and TMA gas are simultaneously or nearly simultaneously adsorbed onto the SiOx film 101 in various parts of the wafer W, starting etching. This improves the uniformity of etching of the SiOx film 101 within the wafer W. Furthermore, after the valves V1 and V2 are opened, the valves V1 and V2 are quickly closed. Specifically, by closing the valves V1 and V2 before the pressure inside the tanks 81 and 82 returns to the initial pressure, etching of the SiN film 102 is suppressed, and the SiOx film 101 can be selectively etched.

[0063] In the above description, the cycle after the initial storage step (between time t1 and time t2) is repeated three or more times, but the number of repetitions is arbitrary. Also, if the required etching amount is small, the cycle may be performed only once without being repeated. In the above process, the valve V10 opening degree is changed simultaneously with the opening of the valves V1 and V2 to reduce the pressure in the processing space 4, but the valve V10 opening degree may be changed slightly before or after the valves V1 and V2 are opened. Changing the valve V10 opening degree at a timing that is shifted by a predetermined time (predetermined time) from the opening of each valve V1 and V2 is also included in reducing the pressure in the processing vessel at a timing corresponding to the opening of the valves, just like changing the valve V10 opening degree simultaneously with the opening of the valves.

[0064] During the initial storage step and subsequent cycles, the pressure sensors 80 in the tanks 81 and 82 continuously transmit detection signals to the control unit 90 at predetermined intervals to monitor the pressures in the tanks 81 and 82. The transmission intervals of these detection signals are shorter than the time during which the valves V1 and V2 are opened to perform the gas release steps (between times t2 and t3 and between times t5 and t6). Therefore, the pressures are detected for each of the gas release steps in which the valves V1 and V2 are open and for each of the other steps in which the valves V1 and V2 are closed. That is, pressures are detected for each period during which the valves V1 and V2 are open and closed. The presence or absence of abnormalities is then monitored based on the detected pressures. Therefore, abnormalities in the device operation can be quickly detected, preventing a decrease in the yield of semiconductor products manufactured from wafers W.

[0065] The following provides a supplementary explanation of the determination of the pressure difference between the tanks 81 and 82 to assist the user in creating a process recipe. To determine this pressure difference, the pressure in each of the tanks 81 and 82 is calculated when the downstream valve V1 or V2 is opened. The following explanation focuses on the tank 81. Assuming that the volume (unit: cc) of the tank 81 is constant, the pressure in the tank 81 changes depending on the gas supply rate (unit: cc) to the tank 81 and the gas discharge rate (unit: cc) from the tank 81. The gas discharge rate is affected by the pressure in the tank 81, but if the valve V1 is opened only for a very short time, this gas discharge rate can be considered to change only depending on the pressure in the tank 81. Furthermore, in a steady-state operating state (the state after time t2 in the chart described above, in which the valves V1 and V2 are repeatedly opened and closed), the pressure in the tank 81 is the same at each opening of the valve V1, and the gas supply rate = the gas discharge rate. The gas supply amount is the flow rate of gas supplied to the tank 81 x time, and the gas flow rate is (HF gas flow rate + N2 gas flow rate) since HF gas and N2 gas are supplied to the tank 81.

[0066] 4 (i.e., the time from when the tank 81 is empty until it is filled with gas and the valve V1 is opened) and the flow rates of the HF gas and N2 gas supplied to the tank 81 from the flow rate adjustment mechanism 60 provided upstream of the tank 81, are set as parameters. The time from time t1 to time 2 x (flow rate of HF gas + flow rate of N2 gas) is the gas supply amount to the tank 81, and this gas supply amount is set to a value that does not exceed the volume of the tank 81. Then, the pressure inside the tank 81 when the valve V1 is opened at time t2 is automatically calculated using this gas supply amount, the volume of the tank 81, and a predetermined formula. As described above, the gas discharge rate due to the opening of valve V1 is determined by the pressure inside tank 81, and the gas discharge rate is calculated using a predetermined formula from the calculated pressure inside tank 81 when valve V1 is opened. As described above, the gas discharge rate = the gas supply rate to compensate for the drop in pressure. Since the flow rate of HF gas + the flow rate of N2 gas have already been set, the time required to refill tank 81 with gas (the time between t4 and t5 and the time between t7 and t8 in the chart of FIG. 4) is also automatically calculated from these gas flow rates and gas supply rates, and the user can know this time.

[0067] As described above, the pressure inside tank 81 when valve V1 is opened can be calculated based on the user's settings. Similarly, the pressure inside tank 82 when valve V2 is opened can be calculated based on the settings of the flow rates of the gases supplied to tank 82 and the time period from time t1 to time t2. The flow rates and supply times of the gases to tank 81 set by the user correspond to first parameters, and the flow rates and supply times of the gases to tank 82 correspond to second parameters. For the pressures inside tanks 81 and 82 calculated in this way (virtual pressures), the difference (virtual pressure difference) between the pressure inside tank 81 and the pressure inside tank 82 at the same time is calculated, and it is determined whether the calculated value falls within an allowable range (i.e., the presence or absence of an abnormality is detected).

[0068] Although it has been assumed that the amount of change in pressure in the tank 81 is constant and the amount of gas discharged varies only depending on the pressure inside the tank 81 due to the valve V1 being open for a very short period of time, in reality, the amount of change in pressure in the tank 81 and the amount of gas discharged vary depending on the pressure inside the tank 81 and the time for which the valve V1 is open. As described above, the pressure inside the tank 81 when the valve V1 is opened at time t2 is automatically calculated. However, a predetermined calculation formula may be prepared so that the pressure after the valve V1 is no longer open is calculated from the time for which the valve V1 is opened and the pressure in the tank 81 when the valve V1 is opened. Then, as described above, the time required to refill the tank 81 with gas after the valve V1 is no longer open may be calculated from the pressure of the valve V1 after the valve V1 is no longer open, calculated using the calculation formula. Note that if gas is supplied to the tank 81 while the valve V1 is open, the decrease in pressure inside the tank 81 due to the opening of the valve V1 is reduced by the amount of gas supplied, which affects the amount of gas discharged from the tank 81 and the amount of pressure change in the tank 81. Therefore, the above formula is set to calculate the pressure after the valve V1 is no longer open, based on the gas supply time and flow rate while the valve V1 is open. The open time of the valve V1, the gas supply time into the tank 81 while the valve V1 is open, and the flow rate of the gas to be supplied are set by the user.

[0069] In calculating the pressure in the tank 81, the increase in pressure in the tank 81 is calculated by multiplying the flow rate of each gas into the tank 81 by the supply time by a predetermined coefficient. Furthermore, assuming that the pressure in the tank 81 decreases by an amount corresponding to the open time of the valve V1, the decrease in pressure in the tank 81 is calculated by multiplying the open time of the valve V1 by a predetermined coefficient. Therefore, the user sets the time between times t1 and t2 in FIG. 4 and the flow rates of the HF gas and N2 gas supplied to the tank 81. The user also sets the time between times t5 and t6 during which the valve V1 is opened during the cycle, the time between times t4 and t5 during which the re-storage step is performed during the cycle, and the flow rates of the HF gas and N2 gas supplied to the tank 81. Based on these settings, the pressure in the tank 81 at times t2 and t5 during which the valve V1 is opened may be calculated. Similar parameters are set for the tank 82, thereby calculating the pressure at times t2 and t5 during which the valve V2 is opened. Then, the pressure difference between the tanks 81 and 82 at times t2 and t5 may be calculated, and a determination may be made as to whether or not the pressure difference falls within an allowable range. Although it has been described that the individual pressures in the tanks 81 and 82 are monitored during processing of the wafer W, the pressure difference between the tanks 81 and 82 may be calculated, as in creating a processing recipe, and the presence or absence of an abnormality may be determined based on the pressure difference.

[0070] Incidentally, when using gases that cause a reaction on the wafer W through the interaction of both gases, such as the HF gas and TMA gas exemplified above, it is sufficient to supply both gases to the wafer W. In other words, it is sufficient to supply one gas to the wafer W while the other gas is adsorbed to the wafer W (while desorption from the wafer W is not complete). Therefore, it is not limited to supplying each gas to the wafer W simultaneously, and each gas may be supplied to the wafer W alternately. In other words, although the periods during which the valves V1 and V2 are opened are the same in the process shown in FIG. 4, the periods during which the valves V1 and V2 are opened may be offset from each other.

[0071] The timing chart shown in FIG. 13 illustrates a process example in which the opening periods of the valves V1 and V2 are staggered. Compared to the process in the timing chart of FIG. 4, the opening of the valve V2 and the supply of TMA gas into the tank 82 are delayed. Specifically, the process involves opening the valve V1 to release HF gas into the processing space 4, closing the valve V1, opening the valve V2 to release TMA gas into the processing space 4, and closing the valve V2. An interval is provided between the closing of one of the valves V1 and V2 and the opening of the other, during which the processing space 4 is purged and evacuated. However, between the supply of one etching gas to the wafer W and the supply of the other etching gas, the one etching gas is desorbed from the SiOx film 101. Therefore, from the perspective of improving the etching performance of the SiOx film 101 and increasing the throughput of the apparatus, it is preferable to align the opening periods of the valves V1 and V2, as in the process described in FIG. 4.

[0072] The valves V1 and V2 may be opened at different times and for overlapping periods. Therefore, for example, the valve V2 may be opened with a slight delay after the valve V1 is opened, so that both the valves V1 and V2 are opened and the gases are supplied from the tanks 81 and 82 to the processing space 4. However, in order to prevent gas from flowing back from one tank to the other via the shower plate 3, it is preferable that the valves V1 and V2 are opened simultaneously.

[0073] Incidentally, in order to quickly diffuse the gas supplied from the tanks 81 and 82 into the processing space 4, it is preferable that the volume of the processing space 4 is as small as possible. Therefore, as illustrated in FIGS. 5 and 6, it is preferable to arrange the stage 5 close to the shower plate 3 that forms the ceiling of the processing vessel 11. However, depending on the processing recipe, it may not be desirable for the stage 5 and the shower plate 3 to be too close to each other. For example, if a processing recipe is set in which the pressure inside the tanks 81 and 82 is relatively high when the valves V1 and V2 are open, the gas discharge pressure from the shower plate 3 may become too high, which may damage the area on the surface of the wafer W directly below the gas discharge ports 33 of the shower plate 3.

[0074] Therefore, when processing wafers W, the stage 5 may be positioned at the same height across the wafer W, but is preferably positioned at a height appropriate for the processing conditions of the wafer W. Similar to FIG. 5, FIG. 14 shows a longitudinal side view of the etching apparatus 1 during processing of wafers W. The height of the stage 5 is lower than that shown in FIG. 5. When the pressure in the tanks 81 and 82 is relatively low when valves V1 and V2 are open, the stage 5 can be positioned at the height shown in FIG. 5, and when the pressure is relatively low, the stage 5 can be positioned at the height shown in FIG. 14. When changing the height of the stage 5 in this manner, it is preferable to change the distance H1 (see FIG. 14) between the upper surface of the stage 5 and the shower plate 3, for example, within a range of 10 mm to 100 mm. When setting multiple processing recipes, the user of the apparatus also sets the height of the stage 5 in association with each processing recipe, and the correspondence is stored in the memory of the control unit 90. When the user selects a processing recipe to use from multiple processing recipes, the stage 5 may be positioned at a height appropriate for the selected processing recipe (i.e., the selected processing conditions) according to the data stored in the memory, and the wafer W may be processed.

[0075] The etching apparatus 1 etches the SiOx film using HF as the halogen-containing gas and NH3 or TMA gas as the basic gas, but the etching process is not limited to this. For example, the film to be etched may be an oxygen-containing Si film other than the SiOx film, or may be a film such as an SiOCN film or a tetraethyl orthosilicate film. Furthermore, gases such as HCl, HBr, HI, and SF6 may be used as the halogen-containing gas other than HF.

[0076] Furthermore, when etching a Si film containing oxygen, amines other than TMA can be used. Specifically, various amine compound gases such as dimethylamine, dimethylethylamine, diethylamine, triethylamine, monotertiarybutylamine, pyrrolidine, and pyridine can be used. As another specific example of the amine compound, a compound in which some or all of the C—H bonds of the above compounds are replaced with C—F bonds (e.g., 1,1,1-trifluorodimethylamine) can be used.

[0077] Furthermore, when etching is performed using the etching apparatus 1, it is particularly effective to selectively etch the film with the shorter incubation time when films with different incubation times, such as the SiOx film 101 and the SiN film 102, are both exposed on the wafer W, but the film to be etched is not limited to this. For example, the etching apparatus 1 can also be used when only a single film is exposed on the surface of the wafer W and this film is the film to be etched.

[0078] The film to be etched is not limited to the oxygen-containing Si film described above, but may be any other Si-containing film. Specifically, it may be a silicon-containing film such as a Si film or a SiGe film. When etching these Si films and SiGe films, F2 gas, IF7 gas, IF5 gas, ClF3 gas, SF6, or the like may be used as a halogen-containing gas, and NH3 gas may be used as a basic gas. In this specification, the phrase "containing" a substance that constitutes a film or gas does not mean that the substance is contained as an impurity, but rather that the substance is contained as a main component constituting the compound.

[0079] For example, when etching a Si film using F2 gas and NH3 gas, depending on the processing temperature of the wafer W when these gases are supplied, the AFS ((NH4)SiF6) that is altered from the Si film may remain, and the AFS may be removed by later heating the wafer W. In this application, etching includes not only the removal of a film by gas, but also the occurrence of alteration alone. In other words, the process of altering the Si film to AFS described above is also included in the etching process.

[0080] Although the above description has been given regarding the selective use of either NH3 gas or amine gas, both gases may be used. Therefore, a mixed gas composed of these NH3 gas and amine gas may be supplied to the wafer W. Furthermore, when supplying such a mixed gas to the wafer W, the NH3 gas and the amine gas may be stored together in the tank 82, or the NH3 gas and the amine gas may be stored in separate tanks and mixed when supplied into the processing chamber 11. Therefore, the number of lines (supply paths) provided with tanks is not limited to two. The halogen-containing gas and the basic gas may be stored in the same tank. However, as described above, there is a risk that the halogen-containing gas and the basic gas may react with each other while stored in the tank, so it is preferable to store them in separate tanks, as described above.

[0081] 4 and 13, when processing wafers W using tanks 81 and 82, valves V1 and V2 are closed immediately after gas release. However, this is not a limitation. As an example of this process, the process shown in the chart in FIG. 15 (which will be described as a continuous supply process for ease of explanation) will be described, focusing on the differences from the process described in FIG. 4 (which may be described as a pulse supply process). At time t11 in FIG. 15, the supply of HF gas and TMA gas to tanks 81 and 82, respectively, begins. Therefore, the operation at time t11 is the same as the operation at time t1 in the pulse supply process. Thereafter, at time t12, valves V1 and V2 are opened to supply gas from tanks 81 and 82 to processing spaces 3A and 3B. The operation at time t12 differs from the operation at time t2 of the pulse supply process in that valves V3 and V4 are not closed, and HF gas and N2 gas are continuously supplied from the HF gas supply source 72 and the N2 gas supply source 73 to the tank 81, and TMA gas and N2 gas are continuously supplied from the TMA gas supply source 74 and the N2 gas supply source 76 to the tank 82.

[0082] The pressure in the tanks 81 and 82 drops suddenly due to the release of pressurized gas inside, then drops gradually and returns to the initial pressure. Then, the valves V1 to V4 are closed, the flow rate control mechanism 60 stops the gas supply from each gas supply source to the tanks 81 and 82, and the opening of the valve V10 is changed from the first opening to the second opening (time t13). Then, the pressure in the processing space 4 drops from the pressure at the position to another pressure, and the exhaust of each gas from the processing space 4 progresses.

[0083] The above series of operations are repeated as a cycle operation to etch a desired amount of the SiO2 film 101. Even in this process, the HF gas and TMA gas can be quickly diffused over the entire surface of the wafer W, so the SiO2 film 101 can be etched with high uniformity in various parts of the surface of the wafer W. However, since the SiN film 102 is exposed to the HF gas and TMA gas for a relatively long time, it is effective to perform the pulse supply process described with reference to FIG. 4 in order to improve the etching selectivity of the SiO2 film 101.

[0084] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive, and various omissions, substitutions, modifications, and combinations may be made in the above-described embodiments without departing from the scope and spirit of the appended claims.

[0085] [Evaluation test] Evaluation tests carried out for this technology will be described below. In these evaluation tests, a substrate on which a pattern was formed was processed using the etching apparatus 1, and the state of the pattern was observed before and after etching. Then, the etching amounts of the SiOx film 101 and the SiN film 102 that were exposed on the surface of the wafer W and formed the pattern were detected before and after etching, and the selectivity (=etching amount of the SiOx film 101 / etching amount of the SiN film 102) was calculated. As evaluation tests 1-1 to 1-3, etching was carried out in different modes.

[0086] In evaluation test 1-1, processing was performed by operating each component of the apparatus as shown in the timing chart of FIG. 16. Differences between the processing shown in FIG. 16 (non-pressurized processing) and the pulse supply processing shown in FIG. 4 will be described. At time t21, gases were supplied to tanks 81 and 82 from flow rate control mechanism 60, while closed valves V1 and V2 were opened. Then, at time t22, valves V1 and V2 were closed, and valve V10, which had been set to a first opening, was opened to a second opening to reduce the pressure inside processing chamber 11. This series of processing steps constitutes a cycle, and wafers W were etched by repeating this cycle five times. Thus, in evaluation test 1-1, although tanks 81 and 82 were provided, gases were supplied to processing space 4 so as not to accumulate or pressurize the gases in tanks 81 and 82. In evaluation test 1-2, the continuous supply processing described in FIG. 15 was performed. The cycle was performed five times. In evaluation test 1-3, the pulse supply processing shown in FIG. 4 was performed. The number of cycles performed after the initial storage step was 25.

[0087] The selectivity ratio was 1.2 in Evaluation Test 1-1, 3.1 in Evaluation Test 1-2, and 52.3 in Evaluation Test 1-3. Therefore, Evaluation Test 1-3 was the most preferable, and Evaluation Test 1-2 was the next preferable. These test results confirmed the effectiveness of storing HF gas and TMA gas in tanks 81 and 82, respectively, and supplying them into the processing vessel 11. Furthermore, it was shown that it is effective to close valves V1 and V2 before all the gases are released from tanks 81 and 82 and the pressures inside the tanks 81 and 82 return to their initial pressures. [Explanation of symbols]

[0088] W wafer 11 Processing container 63, 64 Piping 72, 74 Gas supply source 81, 82 Tanks

Claims

1. supplying each of a first etching gas and a second etching gas containing at least one of an ammonia gas and an amine gas from a gas supply source to a gas supply path; a storing step of storing the first etching gas and the second etching gas in a storage portion provided in the gas supply path and increasing the pressure inside the storage portion; a gas supplying step of opening a valve provided downstream of the reservoir in the gas supply path to supply the first etching gas and the second etching gas stored in the reservoir to a processing vessel containing a substrate therein, thereby etching a first film formed on the substrate; An etching method comprising:

2. the first etching gas is a halogen-containing gas; 2. The etching method according to claim 1, wherein the first film is a silicon-containing film.

3. 3. The etching method according to claim 2, further comprising an opening and closing step of repeatedly opening and closing the valve to repeatedly perform the gas supply step in order to repeatedly etch the first film.

4. The storage step includes: an initial storage step of changing the pressure inside the storage section from a first pressure to a second pressure higher than the first pressure; a re-storing step of returning the inside of the storage section, which has been set to a third pressure lower than the second pressure and higher than the first pressure by performing the gas supplying step, to the second pressure, 4. The etching method according to claim 3, wherein a cycle consisting of the gas supply step and the re-storing step is repeated.

5. a step of reducing the pressure in the processing vessel from one pressure to another pressure at a timing corresponding to the opening of the valve; increasing the pressure in the processing vessel from the other pressure to the one pressure after opening the valve and before opening the valve again; The etching method according to claim 3, comprising:

6. the reservoir includes a first reservoir and a second reservoir, the valves include a first valve and a second valve; the storing step includes a step of storing the first etching gas and the second etching gas in a first storage section and a second storage section, respectively; 3. The etching method according to claim 2, wherein the gas supplying step includes the step of opening the first valve provided downstream of the first reservoir and the second valve provided downstream of the second reservoir.

7. 7. The etching method according to claim 6, wherein the gas supply step includes the step of simultaneously opening the first valve and the second valve.

8. a second film of a type different from the first film is formed on the substrate; 3. The etching method according to claim 2, wherein the valve is closed and the processing chamber is evacuated so that the first film of the first and second films is selectively etched.

9. 9. The etching method according to claim 8, wherein the first film is a silicon oxide film, and the second film is a silicon nitride film.

10. a step of raising and lowering a stage on which the substrate is placed within the processing vessel by a drive mechanism to change the distance between the stage and a ceiling of the processing vessel; The gas supplying step includes:

2. The etching method according to claim 1, further comprising the step of supplying the first etching gas and the second etching gas to the substrate on the stage positioned at a height set according to processing conditions for the substrate.

11. detecting the pressure in the reservoir with a pressure sensor; determining whether or not there is an abnormality based on the pressure; The etching method of claim 3, comprising:

12. The pressure is detected by the valve, which is repeatedly opened and closed.

12. The etching method of claim 11, wherein the etching is performed for each open period and each closed period.

13. a plurality of stages for placing the substrate in the processing vessel are provided in the processing vessel; 2. The etching method according to claim 1, wherein the gas supplying step includes a step of simultaneously supplying the first etching gas and the second etching gas to the substrates placed on the stages.

14. a gas supply source that supplies each of a first etching gas and a second etching gas including at least one of an ammonia gas and an amine gas; a gas flow path through which the first etching gas and the second etching gas are supplied from the gas supply source; a processing vessel that houses a substrate on which a first film is formed and that is connected to a downstream end of the gas flow path; a reservoir provided in the gas flow path; a valve that is provided in the gas flow path downstream of the storage portion, and that is opened to supply the first etching gas and the second etching gas into the processing vessel to etch the first film after the first etching gas and the second etching gas are stored in the storage portion and the storage portion is closed so as to increase the pressure inside the storage portion; An etching apparatus comprising:

15. An etching apparatus as described in claim 14, wherein a protective film is formed on the portion of the processing vessel that comes into contact with the first etching gas and the second etching gas to prevent corrosion caused by the first etching gas and the second etching gas.

16. The etching apparatus according to claim 15, wherein the protective film is made of nickel.

17. Software used in an etching apparatus, comprising: supplying each of a first etching gas and a second etching gas including at least one of an ammonia gas and an amine gas from a gas supply source to a gas supply path; a storing step of storing the first etching gas and the second etching gas in a storage portion provided in the gas supply path and increasing the pressure inside the storage portion; a gas supply step of opening a valve provided downstream of the reservoir in the gas supply path to supply the first etching gas and the second etching gas stored in the reservoir to a processing vessel containing a substrate therein, thereby etching a first film formed on the substrate; Software including.

18. the reservoir includes a first reservoir and a second reservoir, the valves include a first valve and a second valve; the storing step includes a step of storing the first etching gas and the second etching gas in a first storage section and a second storage section, respectively; the gas supplying step includes a step of simultaneously opening the first valve provided downstream of the first storage portion and the second valve provided downstream of the second storage portion, Based on a first parameter set for calculating a virtual pressure in the first storage portion and a second parameter set for calculating a virtual pressure in the second storage portion, 18. The software of claim 17, further comprising the step of detecting an anomaly in a virtual pressure difference between the first reservoir and the second reservoir.

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